Centering and compensating chuck



Feb. 16, 1937. v P. P-G. HALL CENTERING AND COMPENSATING CHUCK 4 Sheets-Sheet 1 Filed March 5, 1936 N VEN TOR PefI'P" a Ha/Z&.

w TNESS Feb. 16, 1937.

P-G. HALL CENTERING AND COMPENSATING CHUCK 4 Sheets-Sheet 2 Filed March 5, 1936 rELF Feb. 16, 1937.

P. P-G. HALL CENTERING AND COMPENSATING CHUCK Filed March 5,1956

4 Sheets-Sheet 5 I INVENTO/f PeZ'er'F-G Hm ZZ a 20 so W; T'IVESS Feb. 16, 1937. P. P-G. HALL CENTERING AND COMPENSATIIQ G CHUCK 4 Sheets-Sheet 4 Filed March 5, 1936 1N VENT 261671 6. ?/a

ITNESS HTTORNEY Patented Feb. 16, 1937 CENTERING AND COMPENSATING CHUCK Peter E-G. Hall, Phiiadelphia, Pa, assignor to The Hall Planetary Company, Philadelphia,

Pa., a corporation of Pennsylvania Application March 5,

1'? Claims.

While a chuck constructed in accordance with the present invention may be advantageously used for supporting many different kinds of work pieces while being subjected to various mechanical operations, it is of particular utility for holding hollow articles, such as pipes and/or those having thin, readily distortable or collapsible walls, in a fixed position while they are being machined, for example, while a thread is being milled thereon.

Chucks heretofore commonly employed for a like purpose usually comprise a plurality of radially movable jaws which are brought against the work simultaneously while it is extended through the body of the chuck so that radially inwardly directed pressure is exerted at circumferentially spaced points upon the work to thereby hold it in position. Such chucks are reasonably satisfactory for the performance of their intended function if the outer surface of the hollow work is exactly concentric with its axis and if the work is sufficiently strong to adequately resist the pressure imposed upon it, as there is then no tendency for the radially inwardly directed pressure exerted by the jaws to spring or distort the work; it therefore results that the work is properly held with respect to the chuck while the machining operation is being performed, and as the machine tool associated with the chuck and employed for the pur pose is adapted to machine the work truly concentric with the axis of the chuck and thus of the work, the machined surface consequently remains concentric with the said axis after the pressure of the chuck jaws is subsequently relieved. If, however, as is frequently the case, the outer surface of the work is slightly nonconcentric or out-of-round with respect to its axis, the pressure exerted by the chuck jaws as they move simultaneously inward springs or distorts the work from its normal condition so that after it is machined in truly concentric relation with the chuck axis and the pressure of the chuck jaws is relieved, it returns to normal condition and thus throws the machined portion out of concentricity, the cross section of said portion becoming slightly eliptical. On the other hand, if the wall section of the work is inadequate to sustain the pressure without collapse, it is often very difficult, if not impossible, to grip the work firmly enough to hold it stationary during the machining operation.

It is therefore a principal object of the present invention to provide a chuck adapted to hold a hollow Work piece in stationary position 1936, Serial No. 67,235

for the performance of some machining operation, such as the cutting of a thread thereon, without appreciable distortion of the work even though its outer surface is normally non-concentric with its axis.

A further object is to provide a chuck adapted to firmly hold work pieces of relatively weak wall section without collapsing them.

A further object is to provide a chuck adapted to properly center the work prior to application thereto of gripping pressure for the purpose of holding it in fixed position in the chuck and to apply that pressure in such manner that the work is held without distortion irrespective of whether its outer surface is truly concentric with its axis or not.

A further object is to provide a chuck of the character aforesaid which is adapted to apply a gripping force to the Work substantially entirely around its outer periphery with the result that the work can be properly held by the exertion of less pressure per unit area of the gripping element than is usually the case when a plurality of separate gripping elements are arranged to contact the work at spaced intervals.

Further objects of the invention are the provision of a work holding chuck adapted for the performance of the aforesaid functions which is simple in construction; comprises parts which are readily machined and not liable to become damaged or broken under the conditions of use to which they are necessarily subjected; which may, and preferably is, so constructed as to enable it to be readily and quickly adapted for holding work of different diameters; which can be rapidly operated by hand or mechanical power to chuck and unchuck the work; which is self-contained and embodies no loose parts liable to become lost or misplaced, and which may be constructed so as to center the work in a plane transverse to its axis and apply the gripping pressure adjacent said plane in one or more circumferential zones axially spaced therefrom, or to center the work in a plurality of axially spaced planes and apply the gripping pressure in one or more circumferential zones lying without said planes.

Other objects, advantages and novel features of design, construction and arrangement comprehended by the invention are hereafter more particularly pointed out or will be apparent to those skilled in the art from the following description of certain chucks constructed in accordance therewith and illustrated in the accompanying drawings, in which Fig. 1 is a fragmentary longitudinal central section of a chuck adapted to center the work in one plane and grip it in a zone adjacent thereto, showing the parts in the positions assumed when the work is being inserted into or withdrawn from the chuck;

Fig. 2 is a similar view but showing the parts in the positions assumed after the work is centered and gripped;

Fig. 3 is a left hand end view on a. reduced scale of the chuck shown in the preceding figures;

Fig. 4 is a fragmentary longitudinal central section of the upper part only of a chuck adapted to center the work in longitudinally spaced planes and to grip it in longitudinally spaced zones adjacent thereto showing the parts in the positions assumed when the work is being inserted into or withdrawn from the chuck;

Fig. 5 is a similar view but showing the parts in the positions assumed after the work is centered and gripped;

Fig. 6, generally corresponding to Fig. 4, shows a chuck adapted to center the work in one plane and to grip it in a plurality of longitudinally spaced zones adjacent thereto;

Fig. '7 is a view of this chuck generally corresponding to Fig. 5;

Fig. 8, also generally corresponding to Fig. 4, shows a chuck of modified construction operative like the chuck of Figs. 1 and 2 to center the work in one plane and grip in a zone adjacent thereto;

Fig. 9 is a view of this chuck generally corresponding to Fig. 5;

Figs. 10 and 11 are respectively a fragmentary enlarged end elevation and a cross section of one form of centering ring which may be utilized in the said chucks;

Figs. 12 and 13 are like fragmentary views of one form of gripping ring which may be employed therein;

Figs. 14, 15 and 16 are respectively a fragmentary enlarged side elevation, an end elevation and a cross section of another form of gripping ring which may be utilized, parts of Figs. 14 and 15 being broken away into fragmentary section; and

Figs. 17, 18 and 19 are respectively like fragmentary views of a form of actuating ring which may be utilized in place of the form shown in the several figures illustrating the chucks.

Throughout the drawings the same characters of reference are used to designate corresponding parts.

In accordance with the preferred practice of the principles of the invention, the work, after being properly located longitudinally in the chuck housing, is first centered coaxially therewith by means constrictable about the work to contact it at spaced points, following which gripping pressure is applied to its periphery to hold it in the centered position to which it has been brought but in such manner as to avoid distortion of the work even though it be out-of-round, this gripping pressure being of course maintained until the ensuing machining or other operation is completed and then relieved, together with the relative light pressure exerted by the centering means, so as to allow the work to be withdrawn from the chuck. For effecting these operations, the chuck essentially comprises a hollow housing through which the work can be passed supporting a compressible centering ring provided with spaced centering points and. co-

operative with an inclined or tapered annular surface in such manner that movement of the ring along the said surface in one direction is operative to constrict the ring and thus bring the centering points into contact with the work and in turn bring it to centered position; a compressible gripping ring, located adjacent the centering ring and through which the requisite movement is communicated to it, which is in itself adapted to suitably grip the centered work; a non-compressible yet flexible actuating ring having an inclined surface cooperative with a corresponding surface on the gripping ring and operative to translate the latter longitudinally toward the centering ring and to then compress it when the actuating ring is moved longitudinally in the housing, and means for effecting such movement of the actuating ring, all as will hereinafter more fully appear.

Mention has already been made of employment of the principles of the invention in chucks respectively adapted to center and hold the work in various ways, and as typifying certain of these I have shown in the drawings and shall herein describe four types of chuck constructed in accordance with said principles but differing specifically in structural details depending on the duty they are respectively intended to perform.

The first of these chucks designed to center the work in one plane and then grip it in a peripheral zone adjacent thereto, is principally illustrated in Figs. 1 and 2 to which I shall now particularly refer, and, as shown, comprises a hollow cylindrical housing I merging into a base 2 adapted for securement to the bed of the machine tco-l with which the chuck is intended for association or to any other support. At one end, which for convenience I shall term the front end, the housing carries an inwardly depending flange 3 while a keeper ring 4 is removably secured to its other end as by cap screws 5, the flange and keeper ring being of somewhat smaller internal diameter than the bore of the housing. Within the housing is slidably fitted a cylindrical sleeve 6 having an inwardly projecting flange l at its rear end and a removable keeper ring 8 at its front end suitably maintained in position as by cap screws 9, the combined length of the sleeve and ring being such that when assembled in the housing they will fit snugly and inhibit longitudinal play between the flange 3 and keeper ring t; the sleeve and ring also form a snug fit in the bore of the housing and are prevented from turning therein by any suitable means such as a key 19. It is thus apparent that by removing keeper ring the sleeve and its associated parts hereinafter described may be slipped endwise out of the housing and as readily reassembled therein.

The inner peripheral surface l2 of ring 8 is inclined or tapered inwardly toward the front end of the chuck, preferably at an angle of about 15 to the axis of the housing, and seated against this surface is a compressible centering ring 53, the outer face of which is tapered in correspondence with the taper of surface i2 and whose inner face is parallel or substantially so to the axis of the housing. This ring, which is normally of internal diameter somewhat greater than the external diameter of the largest pipe '9 or other work the chuck is designed to hold, is so constructed that it can be compressed from this normal condition so as to decrease the length of its inner peripheral surface, and to this end is split transversely as at I4 so that its ends can move toward each other from their normal position as shown in Fig. 1. When this ring is of relatively thin section it is ordinarily of sufiicient inherent compressibility, but in other cases it may be desirable to enhance this quality in any suitable way. Thus, as will be readily understood, the ring may be provided with a plurality of radially directed slots l5, respectively extending inward from its outer surface for a suitable distance as shown in Figs. 10 and 11, or may be slotted or constructed in various other ways to the end that it be sufficiently compressible to yield inwardly under relatively light radial pressure when applied to its outer periphery in the manner hereinafter explained. This ring carries a plurality of centering points ll projecting radially inward from its inner face, three of these points being preferably provided and disposed at intervals of 120 so that when the ring is constricted about the work they will be brought to bear thereon and by reason of their three-point contact therewith center the work accurately in coaxial relation with the ring and in turn with the chuck housing.

Adjacent but normally in spaced relation to the rear face of the centering ring is disposed the gripping ring 20 having its inner face parallel or substantially so with the axis of the housing and its outer face 20 inclined or tapered in the opposite direction to the outer face l3 of the centering ring but preferably at substantially the same angle. This gripping ring is compressible and flexible and to provide the latter characteristic may have radially directed slots 2| extended inwardly from its outer periphery as best shown in Figs. 12 and 13 or arranged in any other suitable way, or, preferably, may be formed of links pivoted together in the manner shown in Figs. 14, 15 and 16 as hereinafter more fully described. To permit constriction of the ring from its nor mal position as shown in Fig. 1, it is split transversely as at 22 in a manner generally similar to the centering ring, and to maintain the gripping ring in proper position in the housing when it is in normal or expanded condition, it is provided with a peripheral flange 23 adapted to engage the inner surface of sleeve 6, this flange being also adapted by engagement with the keeper ring 8 to limit movement of the gripping ring toward the front end of the chuck.

In accordance with my preferred construction and for a purpose which will later more fully appear, yielding means adapted to resist free movement of the rings toward each other are interposed between the centering and gripping rings and may be of any character suitable for the performance of their intended function. Conveniently, said means may therefore consist of a series of coil springs 25 seating at their rear ends in pockets 26 disposed in circumferentially spaced relation in the front part of the gripping ring and bearing at their opposite ends against the rear face of the centering ring, the springs thus acting to normally push the rings apart but being capable of compression to allow them to approach each other.

Within sleeve 6 and rearwardly of the gripping ring is disposed an actuating ring 30 having an inner tapered surface 30' cooperative with the tapered outer surface of the gripping ring, the rear end of which normally telescopes for a short distance within the actuating ring. This latter ring derives its support solely from the gripping ring being at all times clear of sleeve 6, and to permit it to conform to the gripping ring it also is made flexible desirably by providing it with a plurality of radially directed slots 3! extending inwardly from its outer periphery or by constructing it of a plurality of links pivoted together as shown in Figs. 17-19 and hereinafter more fully described. It will be noted, however, that the actuating ring is not transversely split as are the other rings and therefore constantly maintains the same inner circumferential length whereas the effective inner circumferential length of the other rings varies as they are partially constricted or permitted to expand. To restrain the gripping and actuating rings from turning in sleeve 5 without, however, preventing them from moving axially therein, suitable means are provided such as a key 32 extending between the rings and the sleeve.

Suitable means, which may be of any character adapted for the performance of their intended function, are also provided for forcing the actuating ring toward the gripping ring, and in the chuck now being described these means comprise -an annular cam ring 35 seated in sleeve 6 adjacent the rear end of the actuating ring and restrained from revolving by key 32, which is carried rearwardly sufficiently for the purpose, and a movable cam sleeve 36 also seated in sleeve 6, the cam ring and sleeve having intereng-aging camming surfaces, generally designated as 31, on their adjacent ends, a thrust collar 38 being preferably positioned between the rear end of the movable sleeve and the flange I.

cam ring 35 can be forced toward the actuating ring to in turn force the latter toward the gripping ring as will more fully appear when the operation of the chuck is explained. The movable sleeve can be rotated in any convenient way, for example, by an operating handle 39 screwed into the sleeve at its lower end and extending radially outward through a slot 40 in sleeves and housing, the slot being of sufficient length to permit the handle to be turned through an are adequate to properly operate the chuck which with a cam of the design illustrated will approximate 90 as best indicated in Fig. 3, in which the handle is shown in full lines in the position which it occupies in Fig. l and in broken lines in the position it would occupy in Fig. 2, that is, when the chuck is gripping the pipe. The operating handle can be actuated manually or by any suitable mechanical or fluid actuated means.

The operation of the chuck just described is as follows: With the parts in the position of Fig. 1, the work P is moved through the housing in either direction until it is properly located longitudinally with respect thereto. The operating handle 39 is then moved toward the full line position of Fig. 3 which through the cooperation of the cam elements 35, 36 moves the actuating ring toward the front of the chuck, that is, to the left in Figs. land 2, and, in turn, moves the gripping ring and centering ring in like direction, thus causing the latter to travel along tapered surface 12 with consequent constriction of the ring until the centering points I? are brought into contact with and ultimately center the work. As the movement of the centering ring is imparted from the gripping through springs 25, it is apparent that as soon as the resistance afforded by the work against further inward movement of the centering points becomes greater than the combined resistance of Thus by rotating movable sleeve 36 in the proper direction,

the springs further movement of the centering ring is arrested and additional movement of the actuating ring then becomes elfective to constrict the gripping ring about the work, thereby applying the requisite gripping pressure thereto. Thus the amount of pressure applied to the work through the centering points is comparatively light and preferably only a little more than sufficient to properly center the work, although on the other hand by forcing the actuating ring farther and farther onto the gripping ring after the latter engages the work, the gripping pressure applied by the gripping ring can be made as great as may be required to properly grip and hold the work; the gripping pressure is thus fully under the control of the operator through the medium of the handle 39. However, as the gripping ring constricts about the Work it readily conforms to the surface thereof and thus grips it substantially at all points lying within the zone or band defined between the end faces of the ring, while the actuating ring, because of its inherent flexibility, likewise conforms to the changes in shape thereby induced in the gripping ring. It results that if the outer surface of the work be non-concentric with the axis of the chuck, or more or less untrue, the gripping pressure applied through the medium of the gripping ring does not tend to distort the work but merely operates to hold it in fixed position in the housing, while in cases in which the Wall section of the work is comparatively weak its tendency to collapse under the said pressure is much less than when a similar piece of work is gripped at a series of. circumferentially spaced points, as where the gripping pressure is applied through a plurality of radially movable jaws. In short, the action of the gripping ring and method of ap plication of pressure thereby to hold the work stationary may be roughly compared to that of a cord wrapped about the work and pulled upon in opposite directions at its ends, since the ring and the cord conform closely to the surface of the work and exert a substantially equal pressure thereon at all points of their engagement therewith. The work can thus be held securely by the application of relatively light pressure per unit area of the zone engaged by the ring and, as pointed out, without substantial tendency to distort or spring the work should its surface be non-concentric with the axis of the housing. Also, it will be noted that when the gripping ring is in gripping position its flange 23 abuts the keeper plate 3 and thus limits further movement of the ring toward the front of the chuck while of course its movement in the other direction is inhibited by the actuating ring and camming elements so that not only is the work held against rotation but also against axial movement in the housing, and thus maintained in the position to which it was originally brought by the operation of the centering ring and centering points ll, as long as the camming elements are restrained from relative movement. After the machining or other operation has been performed on the chucked work, the cam element 35 is rotated in the opposite direction so as to relieve the pressure on the actuating ring which then tends to automatically free itself from the gripping ring, thus relieving the pressure on the latter 'and permitting it to expand to its normal position, the springs meanwhile pushing it to the right or rearwardly as they expand and thus in turn relieving the longitudinal pressure on the centering ring and permitting it also to expand and assume its normal position. The centering points and gripping ring being thus cleared from the work, the latter can be withdrawn from the chuck by moving it axially in either direction preparatory to insertion of a subsequent work piece.

Figs. 12 and 13 represent on a scale considerably larger than shown in the principal figures, a gripping ring of the type illustrated therein but if preferred a ring of the character shown in Figs. 14-16 inclusive may be employed in lieu thereof. Such a ring is constructed of a plurality of links d5, 56 connected adjacent their extremities by transversely extending pivots ll, sufiicient clearance 48 being provided adjacent one or more of the pivots to allow the necessary expansion and contraction of the ring. A ring of this type is extremely flexible and thus well adapted to conform to the surface of the work but of course has no inherent expandability and consequently when constricted about the work does not tend of itself to return to its normal or expanded condition to thereby clear itself therefrom. Consequently, means such as an annular flat transversely split spring 39 may be seated in a suitable groove in the inner periphery of the ring to supply the requisite capacity for automatic expansion when the pressure of the actuating ring on the outer surface of the gripping ring is relieved.

Likewise, in Figs. 17-19 I have shown a type of actuating ring which may be substituted for the slotted ring shown in the main figures, this ring being formed of a plurality of separate links 55), 5! connected adjacent their ends by pivots 52, and of course suitably tapered on their inner surfaces to conform with the taper of the outer surface of the gripping ring with which the actuating ring is designed to cooperate. An actuating ring of this type is well adapted to con form to the changes in shape of the gripping ring and will frequently be preferred to the type of actuating ring shown in the main figures.

. It will thus be appreciated that the several rings embodied in the chuck may be respectively constructed in various ways as long as they are suitably adapted for the performance of their respective functions as hitherto described, the different types of rings to which I have referred being merely illustrative of certain of the many different specific forms which may be utilized.

In Figs. 4 and 5 I have shown another chuck embodying the principles of the invention but which is adapted to simultaneously center the work in axially spaced planes and to then grip it in axially spaced zones respectively adjacent thereto, a chuck of this character being eminently suitable for certain industrial purposes. For convenience the parts of this chuck corresponding to those heretofore described are designated by the same numerals with the addition of an a while those of the chucks respectively shown in Figs. 6, 7 and 8, 9 are also designated by the same numerals with the addition of a b or a c as the case may be.

This chuck embodies a housing and keeper ring similar to those heretofore described, the housing, however, being of relatively greater length; within it is disposed a sleeve to provided at each end with a removable keeper ring 8a having its inner face tapered inwardly toward the adjacent end of the chuck.

Adjacent each keeper ring is disposed a centering ring Ilia cooperative with the tapered surface I20. of the keeper ring; adjacent each centering ring, a gripping ring Eta, and adjacent each gripping ring, an actuating ring 33a, the construction at each end of the chuck being there for identical with that of the chuck shown in Figs. 1 and 2.

Behind each actuating ring is disposed a cam ring 35:; and between the cam rings, a cam sleeve 36a rotatable by a handle 39a and so designed that when it is turned from the position of Fig. 4.- toward that of Fig. 5 it will move both cam rings simultaneously oppositely outward toward the ends of the chuck and thereby correspondingly move the actuating, gripping, and centering rings in the manner already described, thus first centering the work in both centering rings and then gripping it by means of the gripping rings in axially spaced zones adjacent the planes in which it is centered, all as will be readily appreciated without further description.

The chuck shown in Figs. 6 and 7 is adapted to center the work in one plane and to grip it in a plurality of longitudinally spaced zones lying rearwardly of that plane, and to this end comprises the usual sleeve th and removable keeper ring 8b adjacent the front end thereof together with a centering ring l6?) cooperative therewith. Rearwardly of this centering ring is arranged a gripping ring 2% and actuating ring 39b therefor similarly to the chucks already described, and

V rearwardly of these gripping and actuating rings a plurality of additional gripping and actuating rings, two of each being shown, respectively designated as 292m and Ziiby, 3512a: and Stlby, the tapered surfaces of rings 2cm: and 3822a: being oppositely directed to those of the other rings. In this chuck, however, means somewhat different from those hitherto described for moving the rings longitudinally of the sleeve are provided, namely, a bushing 55 extending forwardly into the sleeve through keeper ring ll) and having, preferably square, external threads cooperative with corresponding threads cut in the rear end ofsleeve iib, a thrust ring 56 being located be tween the forward end of the bushing and the rearmost actuating ring 592211. This bushing is long enough to extend in its forwardly projected position (Fig. '7) for a suitable distance behind keeper ring fl-b and is provided with an operating handle 3% by means of which it can be rotated. Thus, when the bushing is retracted (Fig. 5) the centering ring and the several gripping and actuating rings assume their expanded positions to allow the work to be inserted and withdrawn from the chuck while when the bushing is screwed inwardly it applies the requisite longitudinal thrust, through thrust ring 55 if employed or directly in its absence, first to actuating ring ditty and in turn to the other rings lying forwardly thereof to thereby cause the centering ring to center the work and the several gripping rings to thereafter grip it in their respective zones as will be readily understood. A chuck of this character affords a large area of gripping contact with the work, for of course as many gripping and actuating rings as desired may be utilized, whereby it is possible to hold the work rigidly by applica tion of a relatively light pressure per unit area of the gripping elements, something frequently of great advantage when the work is of relatively weak wall section and readily susceptible to collapse under inwardly directed pressure.

It will of course be appreciated that instead of a threaded bushing, camming or any other suitable means may be utilized for moving the rings in this type of chuck and further that in place of camming elements 35, 35 a threaded bushing or other suitable means may be utilized for a like purpose in the chucks heretofore described.

It is preferable that the centering of the work be accomplished with relatively light pressure, a condition conveniently brought about by the interposition of the yielding means between the centering and the gripping rings as hitherto described, but if desired said means may be dispensed with and the gripping ring arranged todirectly engage the centering ring as in the chuck shown in Figs. 8 and 9. This chuck is adapted to center the work in one plane and grip it in a zone adjacent thereto similarly to the chuck shown in Figs. 1 and 2 to which it otherwise generally corresponds insofar as the arrangement of the gripping and actuating rings is concerned although the movement of these rings is shown as accomplished through the medium of a threaded bushing 550 instead of through camming elements. However, the tapered surface I20 of keeper ring is disposed at a much greater angle to the axis of the chuck than the corresponding surfaces of the keeper rings heretofore described and that part I3c of the centering ring designed for cooperation therewith is correspondingly more sharply tapered, with the result that the radially directed component of the force exerted on the centering ring by the gripping ring when the latter is moved in a direction to cause the centering ring to contract is materially less than would be the case if the cooperating tapered surfaces formed a smaller angle to the axis; in consequence but a relatively light pressure is exerted by the centering ring on the work even though a very heavy pressure is exerted by the operating means upon the actuating and gripping rings.

Since the capacity of a given chuck for holding work pieces of different diameter is limited, the range being primarily determined by the maximum diameters of the gripping rings when in fully expanded and fully contracted position, I therefore prefer, as shown, to arrange the principal operating parts in a sleeve or bushing 6 removably positioned in the main housing so that when it is desired to operate on work of greater or smaller diameter than the chuck is adapted to hold, the sleeve can be removed from the housing and replaced with another sleeve containing operating mechanism suitable for such work, an operation very readily accomplished by merely taking off keeper ring 4, unscrewing the operating handle, if necessary, sliding out the sleeve, inserting the new one and reassembling the keeper and handle. The main housing thus remains undisturbed on the bed of the machine tool and the change-over can be made in a very few minutes. However, when the chuck is intended for continuous operation on work of but one diameter, it may be preferred to omit the sleeve or equivalent member and dispose the rings and other actuating mechanism directly in the main housing, tapering the inner surface of flange 3 for cooperation with the centering ring and omitting keeper ring 8, as will be readily understood.

While I have herein described several chucks embodying the principles of the invention and respectively adapted to operate in different ways upon a work piece, it will be understood I do not thereby desire or intend to restrict or confine myself thereto in any way as the said principles may be employed in numerous other mechanisms designed for centering and/or gripping work pieces and means other than those to which I have referred may be utilized for carrying them into effect while the details of design, construction and arrangement of the various elements comprised in the chucks which I have chosen as illustrative of my invention may be varied in numerous particulars without departing from the spirit and scope thereof as defined in the appended claims.

Having thus described my invention, I claim and desire to protect by Letters Patent of the .i United States:

1, A work-holding chuck comprising a housing providing an annular tapered surface, an annular compressible element cooperative with said surface, a second annular compressible element having an outer surface tapered oppositely to said annular surface'disposed adjacent the first ele- .ment, an annular flexible actuating element having an inner tapered surface cooperative with the tapered surface of the second element, and means for translating the flexible element axially of the housing to thereby initially move the second element axially therein and in turn, move the first element along the annular tapered surface of the housing to thereby constrict that element about a work piece extended therethrough and center it axially of the housing, and to thereafter constrict the second element about the piece to hold it in fixed position.

2. A Work-holding chuck comprising a housing providing an annular tapered surface, an annular compressible element cooperative with said surface, a second annular compressible element having an outer surface tapered oppositely to said annular surface disposed adjacent the first element, yielding means interposed between said elements, an annular flexible actuating element having an inner tapered surface cooperative with the tapered surface of the second element, and means for translating the flexible element axially of the housing to thereby initially move the second element axially therein and in turn, through said yielding means, move the first element along the annular tapered surface of the housing to thereby constrict that element about a .work piece extended therethrough and center it axially of the housing, and to thereafter constrict the second element about the piece to hold it in fixed position.

'3. A work holding chuck comprising a hollow housing providing a tapered surface, a compressible centering element cooperative with said surface, a flexible and compressible gripping element adjacent thereto, saidgripping element having a surface oppositely tapered to that of the centering element, a flexible actuating element adapted to surround the gripping element having an inner tapered surface cooperative therewith, and means for translating the actuating element axially of the housing to thereby first move the gripping element toward the centering element and correspondingly move the latter alongthe tapered surface of the housing to constrict said element about a work piece extended through the several elements and thereby center it in the housing, and to then constrict the gripping element about the piece to hold it in fixed position.

4. A work-holding chuck comprising a hollow housing providing an annular tapered surface, a compressible centering element cooperative with said surface, a flexible and compressible gripping element in axially spaced relation thereto, yielding means interposed between said elements, said gripping element having a surface oppositely tapered to'that of the centering element, a flexible actuating element surrounding the gripping element having an inner tapered surface cooperative therewith, and means for translating the actuating element axially of the housing to thereby initially move the gripping element toward the centering element and, through the said yielding means, correspondingly move the centering element along the tapered surface of the housing to constrict said element about a work piece extended through the elements and thereby center it in the housing and to thereafter constrict the gripping element about the piece to hold it in fixed position.

5. A work-holding chuck comprising a hollow housing providing an annular tapered surface,

a compressible centering ring having an outer surface cooperative with said tapered surface, inwardly projecting centering points carried by said ring, a flexible compressible gripping ring axially spaced from the centering ring having an outer surface oppositely tapered to that of said ring, a flexible actuating ring having an inner tapered surface surrounding the gripping ring, and means for moving the actuating ring axially of the housing after the work is extended therethrough to thereby initially translate the gripping ring axially thereof and in turn move the centering ring along the inclined surface of the housing to constrict said' ring about the work and center it axially of the housing, and to thereafter constrict the gripping ring about the Work to hold it in fixed position in the housing.

6. A Work-holding chuck comprising a hollow housing providing an annular tapered surface, a compressible centering ring having a tapered surface engaging said surface of the housing, a compressible deformable gripping ring having an outer surface oppositely tapered to that of the centering ring disposed adjacent but spaced from the latter, a non-compressible but deformable actuating ring having an inner tapered surface receiving the smaller end of the gripping ring, and means for translating the actuating ring toward the gripping ring to thereby initially move the gripping ring toward the centering ring and cause it to ride on the inclined surface of the housing and constrict about the work when extended therethrough to center the work in the housing, and to thereafter constrict the gripping ring about the work to hold it in centered and fixed position within the housing, the actuating ring conforming to changes in shape of the gripping ring as the latter conforms to the surface of the work.

'7. A work-holding chuck comprising a hollow housing providing an annular tapered surface, a compressible centering ring having a tapered surface engaging said surface of the housing, a compressible deformable gripping ring having an outer surface oppositely tapered to that of the centering ring disposed adjacent but spaced from the latter, a plurality of springs interposed between said rings, a non-compressible but deformable actuating ring having an inner tapered surface receiving the smaller end of the gripping ring, and means for translating the actuating ring toward the gripping ring to thereby initially move the gripping ring toward the centering ring and, through said springs, cause it to ride on the inclined surface of the housing and constrict about the work when extended therethrough to center th work in the housing, and to thereafter constrict the gripping ring about the work to hold it in centered and fixed position within the housing, the actuating ring conforming to changes in to the surface of the work.

8. A work-holding chuck comprising a hollow housing having adjacent each end an annular tapered surface, a compressible ring having a tapered outer surface seating against each of said annular surfaces, a flexible compressible gripping ring axially inwardly spaced from each of said centering rings, each gripping ring having its outer surface oppositely tapered to that of the adjacent centering ring, a flexible actuating ring receiving the smaller end of each gripping ring and having its inner surface tapered oppositely thereto, and means operableto simultaneously translate the actuating rings in opposite directions toward the respectively adjacent gripping rings to thereby initially move the latter toward the centering rings and cause them by coaction with said annular surfaces to constrict about a work piece extended through all the rings to thereby center it with the housing and to thereafter constrict both gripping rings about said piece to hold it in fixed and centered position, the actuating rings being adapted to conform to their adjacent gripping rings as the latter conform to the surface of the work piece as they are brought against it.

9. A work-holding chuck comprising a hollow housing having adjacent each end an annular tapered surface, a compressible ring having a tapered outer surface seating against each of said annular surfaces, a flexible compressible gripping ring axially inwardly spaced from each of said centering rings, each gripping ring having its outer surface oppositely tapered to that of the adjacent centering ring, a flexible actuating ring receiving the smaller end of each gripping ring and having its inner surface tapered oppositely thereto, yielding means interposed between each gripping ring and the adjacent centering ring, and means operable to simultaneously translate the actuating rings in opposite directions toward the respectively adjacent gripping rings to thereby initially move the latter toward the centering rings and, through said yielding means, cause them by coaction with said annular surfaces to constrict about a work piece extended through all the rings to thereby center it with the housing and to thereafter constrict both gripping rings about said piece to hold it in fixed and centered position, the actuating rings being adapted to conform to their adjacent gripping rings as the latter conform to the surface of the work piece as they are brought against it.

10. A work holding chuck comprising a hollow housing providing axially spaced oppositely tapered annular surfaces adjacent its extremities, a compressible centering ring seating against each of said surfaces, a flexible compressible gripping ring having its outer surface tapered oppositely to the adjacent annular surface axially spaced inwardly from each centering ring, a pair of flexible actuating rings located between and respectively adapted to receive the smaller ends of the gripping rings and having their inner surfaces tapered oppositely thereto, yielding means interposed between each gripping ring and the adjacent centering ring, and means disposed between the actuating rings operable to simultaneously move said rings oppositely outwardly toward the ends of the housing to thereby initially translate the gripping rings toward the centering rings and, through said yielding means, cause them to ride up on said annular surfaces and constrict about a Work piece extended through all the rings to center it coaxially with the housing, and to thereafter constrict both gripping rings about said piece to hold it inflxed and centered position, the actuating rings being adapted to conform to their adjacent gripping rings as the latter in turn conform to the surface of the work piece.

11. A work-holding mechanism comprising a hollow housing having an inner annular tapered surface, a compressible centering ring having its outer surface engaging said annular surface, a plurality of flexible compressible gripping rings spaced from the centering ring having tapered outer surfaces, flexible actuating rings having inner tapered surfaces respectively receiving the smaller ends of the adjacent gripping rings, and means operable to translate one of the actuating rings axially of the housing to thereby initially correspondingly move the other gripping and actuating rings and cause the centering ring to ride on said annular surface and constrict about a work piece to center it in the housing and to thereafter cause all of the gripping rings to constrict about said piece to hold it in fixed position, the actuating rings conforming to their respective gripping rings as the latter conform to the surface of the work.

12. In a work-holding mechanism, a flexible compressible gripping ring having an outer tapered surface, a flexible but non-compressible actuating ring adapted to receive the smaller end thereof, and means for moving the actuating ring upon the tapered surface of the gripping ring to thereby cause the latter to constrict about and conform to the surface of a work piece extended therethrough, the actuating ring being adapted to correspondingly conform to the outer surface of the gripping ring.

13. In work-holding mechanism, a supporting element, a compressible ring within said member having a tapered outer surface, a flexible but non-compressible ring adjacent the smaller end of the gripping ring having its inner surface tapered in conformity therewith, and means for moving the actuating ring along the tapered surface of the gripping ring to thereby constrict the latter about a work piece extending therethrough and cause it to conform the surface thereof and to exert inwardly directed pressure thereon, the actuating ring being adapted to correspondingly conform to changes in contour of the gripping ring induced by lack of concentricity of said surface with the axis of the supporting element.

14. In work-holding mechanism a hollow supporting element, a compressible gripping ring disposed th rein having an outer tapered surface, a flexible but non-compressible actuating ring adapted to receive the smaller end of the gripping ring, means preventing rotation of the rings in the elements, and means for translating the actuating ring toward the gripping ring to thereby cause the latter to constrict about a piece of work extending therethrough, the gripping ring being adapted to conform to the surface of the work as it engages therewith and the actuating ring being free to correspondingly conform to resultant changes in shape of the gripping ring.

15. In work holding mechanism, a gripping ring having a tapered outer surface and comprising a plurality of links and pivots connecting the links, at least one of the links being arranged for limited endwise movement with respect to a pivot to thereby permit expansion and contraction of the ring.

16. In work-holding mechanism, a gripping ring having a tapered outer surface and comprising a plurality of relatively movable links and pivots interconnecting said links, at least one of --said links being capable of limited endwise moveing a plurality of relatively movable links and pivots interconnecting said links, at least one of said links being capable of limited endwise movement with respect to a pivot to thereby permit expansion and contraction of the ring,

and a transversely split radially expandible spring seated within the links operative to normally maintain the ring in fully expanded condition.

PETER P-G. HALL. 

